To connect a light sensor to an Arduino, connect the light sensor in series with a resistor between 5V and GND. The light sensor used in this tutorial is a photoresistor, which is also called light-dependent. A light sensor is a great solution if someone in your household tends to leave certain lights on. This is easily achieved by replacing any existing light switch with a motion sensor light switch. You could also install a brand new LED light and motion sensor somewhere like an unfinished basement or. This Arduino Light sensor circuit is a simple example that shows you how to connect light sensors such as photoresistors, photodiodes, and phototransistors, to an Arduino. For this project, you'll need: I've recently posted a tutorial about this project on YouTube explaining everything you can read on this article.